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Over Sunday lunch, the Collins family, who reside on the 13th floor of a London tower block,
discuss the forthcoming conversion to decimal currency. The
male members of the family are confident about the change but the mother,
daughter and granny are apprehensive. Granny Collins is particularly anxious
about the new system and wakes up screaming from her Sunday afternoon nap during
a surreal nightmare in which decimal points are fired at her from all sides. The
fashion-conscious teenage daughter, Sandra, is less concerned and busies herself
trying on a series of fashionable wigs.

At school Peter Collins' maths teacher explains the how the decimal system
works and urges the students to pass on their knowledge to their elders who
might find it more difficult to make the change.

Mrs Collins, addressing her family through the kitchen hatch, relays her
concern that the new system might make it easier for shop-owners to put the
prices up, but Mr Collins assures her that there are readily available decimal
conversion tables which will prevent this. Granny Collins' opposition to the
system is steadfast, however, and she threatens to go on a hunger strike in
protest.

D-Day arrives and the Collinses are having breakfast together - everyone,
that is, except Granny, who has locked herself in her bedroom. Mrs Collins
wonders whether she should to go to the post office to convert her old money
into new money. Her husband tells her that this is unnecessary since old money
will still be in circulation.

Left alone in the flat, Granny Collins opens the door to the milkman who
tries to explain the new coinage to her in simple terms, but only exacerbates
her confusion. She starts to cry.

The other members of the family start using the new decimal system in their
respective situations: Mrs Collins at the bakery and the grocer; Mr Collins at
work in his office; Sandra Collins at the boutique and Peter at school. Sandra
struggles the most and is unable to complete a decimal transaction with a
customer.

Peter kindly gives his grandmother a lesson in decimalisation and, after much
patience on his part, Granny Collins does finally 'get the point'. When they
visit Sandra at the boutique, Granny surprises a group of confused young
shoppers with her grasp of the new system.